The long-term goal of our research is to evaluate in a quantitative manner the contribution that the baroreceptor reflex makes to the "homeostasis" of the body. Our general approach will be characterized by systems approach whenever it is appropriate. In our analyses we attempt to decompose the system in such a manner that the derived pieces of experimental information can be integrated into a holistic picture of reflex control of the entire circulation. There are three immediate aims of the present proposal: a. The first is to solve two technical (but extremely important) problems associated with chronic dog experiments on the reflex. b. The second is to continue and develop the on-going studies on the effects of head-level change and hemorrhage on arterial pressure and the roles of the carotid sinus baroreceptor reflex in these daily perturbations. c. The third is to analyze the reflex performance in acute experiments which cannot be achieved in unanesthetized animals.